Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 251719 AAC
AFDDVN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1219 PM CDT MON APR 25 2016

...AVIATION UPDATE...

.UPDATE...
ISSUED AT 1029 AM CDT MON APR 25 2016

STILL ON TRACK FOR STRONG TO SEVERE STORMS THIS AFTERNOON AS H5
AND H3 JET APPROACHES THE AREA. THIS WITH A SURGE IN THE SFC
BOUNDARY WILL LEAD TO CONVERGENCE AT THE SFC AND STORM INITIATION
AROUND 19Z. BEST CHANCES FOR SEVERE WEATHER WILL BE IN OUR
ILLINOIS ZONES AS STORMS MATURE. DEEP LAYER SHEAR AND HIRES MODELS
SUGGEST ISOLATED SUPERCELLULAR STRICTURES WITH LARGE HAIL BEING
THE MAIN THREAT. MAIN LIMITING FACTOR WILL BE STORM COVERAGE AS
SOME CAMS DO NOT PRODUCE ANY STORMS. THAT SAID ANYTHING THAT DOES
DEVELOP WILL HAVE THE CHANCE TO BECOME SEVERE. HAVE UPDATED POP
GRIDS WITH CURRENT TIMING AND CHANGED THE SKY GRIDS AS WELL. NO
OTHER CHANGES ARE EXPECTED AT THIS TIME.

&&

.SYNOPSIS...
ISSUED AT 315 AM CDT MON APR 25 2016

LOW PRESSURE WAS LOCATED IN EXTREME EASTERN SD WITH A WARM FRONT
INTO SOUTHERN WI AND A COLD FRONT EXTENDING FROM THE LOW INTO
EXTREME EASTERN NEB AND THEN TO SW KS. LINE OF THUNDERSTORMS THAT
WAS IN CENTRAL IA EARLIER IN THE NIGHT HAS RAPIDLY DECAYED THE
PAST COUPLE OF HOURS TO ONLY A FEW SHOWERS. THIS IS DUE TO A MUCH
MORE STABLE AIRMASS OVER THE DVN CWA AND LACK OF SHEAR.

TEMPERATURES WERE MILD EARLY THIS MORNING AS EXPECTED WITH A
STEADY SOUTH WIND AND CLOUD COVER. 3 AM TEMPERATURES WERE MAINLY
IN THE LOWER TO MID 60S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT MON APR 25 2016

FORECAST FOCUS ON THE POTENTIAL FOR ISOLATED STRONG OR SEVERE
THUNDERSTORMS LATER TODAY.

TODAY...WHAT FEW SHOWERS THERE ARE EARLY THIS MORNING WILL
CONTINUE TO FADE AWAY LEAVING THE MORNING HOURS (AFTER 6 AM) DRY.
THEN THE FOCUS WILL BE ON IF ANY CONVECTION CAN ERUPT LATER THIS
AFTERNOON AND EVENING. LOW PRESSURE WILL TRACK ACROSS SOUTHERN MN
AND BE NEAR LA CROSSE WI BY EVENING. A WEAK COLD FRONT WILL DRAG
SOUTHEAST INTO THE DVN CWA THIS AFTERNOON. AHEAD OF THE FRONT
TEMPERATURES SHOULD WARM INTO THE UPPER 70S TO LOWER 80S. WITH
DEWPOINTS IN THE MID 50S TO AROUND 60 THIS SHOULD YIELD MUCAPES OF
ABOUT 2000 J/KG AND MLCAPE TO 1000 J/KG. A 50 KNOT MID LEVEL WIND
MAX WILL APPROACH THE AREA AT PEAK HEATING WITH MODERATE DEEP
LAYER SHEAR OF 40 KNOTS. ANY STORMS DEVELOPING IN THIS ENVIRONMENT
SHOULD BE ABLE TO PRODUCE LARGE HAIL AND DAMAGING WINDS.

HOWEVER...THE BIG PROBLEM IS THE LACK OF SUFFICIENT CONVERGENCE
NEAR THE FRONT AS THE WINDS VEER UNIDIRECTIONAL FROM THE SOUTHWEST.
THE HRRR KEEPS THE CONVECTION IN WI CLOSER TO THE SURFACE LOW AND
BETTER FORCING WHILE THE SPC 4.0 KM WRF-NMM FIRES UP CONVECTION
EAST OF THE MS RIVER NOT UNTIL THIS EVENING. THEREFORE...HAVE
KEPT MENTION OF CHANCE POPS IN THE 20-40 PERCENT RANGE AND MAINLY
ALONG AND EAST OF THE MS RIVER LATER THIS AFTERNOON AND EVENING...
AHEAD OF THE FRONT. SPC DOES HAVE A SLIGHT RISK EAST OF THE MS RIVER.
AT THIS TIME WILL KEEP COVERAGE OF THE STORMS TO ISOLATED TO
SCATTERED BUT THE POTENTIAL IS THERE FOR A DRY FROPA...AND LET DAY
SHIFT MONITOR TRENDS.

TONIGHT...ASSUMING CONVECTION FORMS LATER THIS AFTERNOON AND
EVENING THE FRONT WILL HAVE PUSHED EAST OF THE DVN CWA BY LATE
EVENING ENDING ANY RAIN CHANCES. WEST WINDS SHOULD BRING SOMEWHAT
DRIER AIR INTO THE CWA SO LOWS TONIGHT WILL BE COOLER...IN THE 50S.
SKIES WILL BECOME CLEAR OR PARTLY CLOUDY BEHIND THE FRONT.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM CDT MON APR 25 2016

THE FORECAST OF VERY ACTIVE SYNOPTIC PROGRESSIVE LOW PRESSURE
SYSTEMS REMAINS FORECAST BY ALL GLOBAL MODELS TONIGHT FOR THE
EXTENDED FORECAST. THE TREND THAT THESE SYSTEMS WILL PASS JUST SOUTH
OF OUR CWA...OR THROUGH OUR SOUTHERN CWA CONTINUES TO SUGGEST
EXTENDED PERIODS OF NEAR 100 PERCENT POPS WILL BE REQUIRED FOR LATE
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AND POSSIBLY THURSDAY. ANOTHER
SYSTEM ON THE HEELS OF THE DEPARTING THURSDAY LOW APPEARS SIMILAR
WITH WIDESPREAD STRATIFORM RAIN/EMBEDDED THUNDER FOR LATE FRIDAY
NIGHT THROUGH THE ENTIRE UPCOMING WEEKEND AND POSSIBLY EARLY WEEK
AHEAD. THAT SYSTEM AS THE MOMENT IS SUGGESTED TO END THE PROGRESSIVE
NATURE OF THE SYNOPTIC FLOW...AND CUT OFF INTO A BROAD UPPER LOW
OVER THE EASTERN HALF OF THE CONUS. THIS IS THE CASE IN BOTH THE GFS
AND EC 00Z RUNS. IN ANY CASE...RAIN...AND PLENTY OF IT....IS
FORECAST THIS UPCOMING WEEK...WITH SOME BOUTS OF EMBEDDED THUNDER
LIKELY AS WELL DURING PERIODS OF STRONG WARM ADVECTION ALOFT.

AT THE TIME...WHILE THE WEEK LONG PERIOD OFFERS THE POTENTIAL FOR
WIDESPREAD 1 TO 2 INCHES OF RAIN...WITH SOME AREAS POSSIBLY SEEING
MORE IN MESOSCALE BANDS OF ACTIVITY. THE RAINFALL RATES OVER ALL
SEEM TO OFFER A SOMEWHAT MORE BENIGN FLASH FLOODING FORECAST...AND
A SLOWLY EVOLVING RIVER RISE POTENTIAL.

TEMPERATURES TUESDAY UNDER SHORT TERM HIGH PRESSURE AND LITTLE COLD
ADVECTION SHOULD TOP OUT WELL INTO THE 70S...MAKING FOR A CERTAIN
CANDIDATE FOR THE MOST PLEASANT DAY THIS WEEK. ONCE RAIN AND CLOUDS
ARRIVE TUESDAY NIGHT...THE NEXT DRY DAY WITH ANY PREDICTABILITY MAY
BE FRIDAY. WEDNESDAY THROUGH THURSDAY WILL SEE FAR COLDER
TEMPERATURES AS IN THE LOWER 50S TO LOWER 60S FROM NORTH TO
SOUTH...AS RAIN COOLED AIR PERSISTS NORTH OF THE WARM FRONT. AT THIS
TIME...IT APPEARS THE WET AND CLOUDY WEATHER WILL KEEP US WELL BELOW
NORMAL WELL INTO NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1214 PM CDT MON APR 25 2016

MVFR CONDITIONS WILL GIVE WAY TO VFR THIS AFTERNOON AND EVENING AS
A COLD FRONT PUSHES THROUGH THE AREA. THE MVFR CIGS AT CID AND DBQ
WILL NOT LAST MUCH LONGER AS THIS FIELD WILL BREAK UP INTO A BAND
CU TO TCU. EAST OF THE MISSISSIPPI RIVER....THUNDERSTORMS ARE
EXPECTED TODAY. TOMORROW AM...GUIDANCE IS HINTING AT MVFR FOG AND
EVEN LOW MVFR CIGS. THINK DBQ HAS THE BEST CHANCE FOR THIS AT THIS
TIME. IT IS POSSIBLE THAT CID MAY NEED TO HAVE THIS INCLUDED IN
LATER TAF ISSUANCES.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...GIBBS
SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...ERVIN
AVIATION...GIBBS



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